Morse.js

/*!
 * MorseJs JavaScript Object
 * https://github.com/JoshuaCarroll/MorseJs/
 *
 * Copyright Joshua Carroll and other contributors
 * Released under the MIT license
 */

var MorseJs = {
    _wpm: 20,
    setWpm: function(wpm) {
        this._wpm = wpm;
        this._ditLength = 1.2/this._wpm;
        this._dahLength = (1.2/this._wpm)*3;
    },
    _context: {},
    _oscillator: {},
    _gain: {},
    init: function() {
        this._context = new (window.AudioContext || window.webkitAudioContext)();
        this._ditLength = 1.2/this._wpm;
        this._dahLength = (1.2/this._wpm)*3;
        this._oscillator = this._context.createOscillator();
        this._oscillator.type = 'sine';
        this._oscillator.frequency.value = 750;
        
        this._gain = this._context.createGain();
        this._gain.gain.value = 0;
        
        this._oscillator.connect(this._gain);          // Sound to gain
        this._gain.connect(this._context.destination); // Gain to output
        this._start();
        
        console.log("%c                                                                                                                   \r\n" +
                    "  .___                     MorseJs © 2017 Joshua Carroll, Released under the MIT license                     -.-.  \r\n" +
                    "                                    https://github.com/JoshuaCarroll/MorseJs/                                      \r\n" + 
                    "                                                                                                                   \r\n" +
                    "               Usage: MorseJs.Play(string TextToSend, [int SpeedInWordsPerMinute, int ToneFrequency]);             \r\n" +
                    "                      MorseJs.Play(\"cq cq de n5jlc k\");                                                            \r\n" +
                    "                      MorseJs.Play(\"cq cq de n5jlc k\", 25);                                                        \r\n"+
                    "                      MorseJs.Play(\"cq cq de n5jlc k\", 25, 500);                                                   \r\n"+
                    "                                                                                                                   ", "background: #222; color: #bada55;");
        
        return this;
    },
    _start: function() {
        this._oscillator.start();
    },
    _stop: function() {
        this._oscillator.stop();
    },
    _ditLength: 0,
    _dahLength: 0,
    _playCharacter: function(character, startTime) {
        for(var i = 0; i < character.length; i++) {
            switch(character[i]) {
            case '.':
                this._gain.gain.setValueAtTime(1.0, startTime);
                startTime += this._ditLength;
                this._gain.gain.setValueAtTime(0.0, startTime);
                break;
            case '-':
                this._gain.gain.setValueAtTime(1.0, startTime);
                startTime += this._dahLength;
                this._gain.gain.setValueAtTime(0.0, startTime);
                break;
            }
            
            if (i+1 < character.length) {
                startTime += this._ditLength; //Inter-element gap
            }
        }
        return startTime;
    },
    Play: function(words, speed, toneFrequency) {
        var startTime = this._context.currentTime;
        
        if (speed != null) {
            this.setWpm(speed);
        }
        
        if (toneFrequency != null) {
            if (this._oscillator.frequency.value != toneFrequency) {
                startTime += 1;
            }
            this._oscillator.frequency.value = toneFrequency;
        }
        
        words = words.toUpperCase();
        
        for (var i = 0; i < words.length; i++) {
            if (words[i] == ' ') {
                startTime += this._ditLength * 7; // Medium gap (between words)
            }
            else if (this.codes[words[i]] != undefined) {
                startTime = this._playCharacter(this.codes[words[i]], startTime);
                startTime += this._ditLength * 3; // Short gap (between letters)
            }
        }
        
        // Returns the length of the message in seconds.
        return startTime - this._context.currentTime;
    },
    codes: {
        "A": ".-",
        "B": "-...",
        "C": "-.-.",
        "D": "-..",
        "E": ".",
        "F": "..-.",
        "G": "--.",
        "H": "....",
        "I": "..",
        "J": ".---",
        "K": "-.-",
        "L": ".-..",
        "M": "--",
        "N": "-.",
        "O": "---",
        "P": ".--.",
        "Q": "--.-",
        "R": ".-.",
        "S": "...",
        "T": "-",
        "U": "..-",
        "V": "...-",
        "W": ".--",
        "X": "-..-",
        "Y": "-.--",
        "Z": "--..",

        "1": ".----",
        "2": "..---",
        "3": "...--",
        "4": "....-",
        "5": ".....",
        "6": "-....",
        "7": "--...",
        "8": "---..",
        "9": "----.",
        "0": "-----",

        ".": ".-.-.-",
        ",": "--..--",
        "?": "..--..",
        "'": ".----.",
        "!": "-.-.--",
        "/": "-..-.",
        "(": "-.--.",
        ")": "-.--.-",
        "&": ".-...",
        ":": "---...",
        ";": "-.-.-."
    }
}.init();